Yes Bo3C and I think the info is in savant and sorcerer, too now. I remember I was a bit surprised at the frequency of demesnes at first but when you take into account all those gods gone rogue, outcasts, celestial exalts and whatnot then even the huge numbers presented in canon will not prevent wars over minor manses.
Don't forget that the frequencies were what Creation origianlly came up with.
 Lots of geomantic landscaping by the Solars in the First Age (and other entities since) could have altered the distribution and quality of the demesnes/Manses significantly.